LITTLE ROCK  A winter storm brought slick conditions to much of the northern half of the state Thursday, coating trees with ice, prompting schools and businesses to close for the day and turning travel in some places treacherous.

The National Weather Service said early Thursday afternoon that Harrison, Mountain Home and Marshall had each recorded a quarter-inch of freezing rain while Jasper had more than a third of an inch. In Batesville, a half inch of ice was reported and more than 2,000 people were without power by 1:30 p.m.

In Pulaski County, where much of the precipitation fell as a cold rain sometimes accompanied by thunder, lightning and hail, the weather service recorded only a tenth of an inch of ice. In Garland County, the lightning was blamed for a fire at a house southwest of the Pleasant Hill community.

The storm had moved out of some parts of the state by the early afternoon, but an ice storm warning remained in effect until 4 p.m. for Baxter, Cleburne, Fulton, Independence, Izard, Marion, Searcy, Sharp, Stone and Van Buren counties. A winter weather advisory remained in effect for several other counties, though additional icing was expected to be minimal.

The weather service warned earlier Thursday that travel could be "dangerous or impossible" in some areas because of the storm and that power outages were likely.

There were reports of a spate of traffic accidents, including the one causing a backup on Interstate 40 near the U.S. 65 exit at Conway. Eastbound I-40 was open at 7 a.m., but the westbound lanes were blocked through the afternoon, and a short detour onto U.S. 65 had been created. By noon, traffic was backed up three miles on the interstate.

That collision between two semi trucks occurred sent one toppling onto its side and another partially down an embankment between the two sides of the highway. Officials on scene said both drivers suffered injuries believed to be minor.

In Prairie County, I-40 lanes both eastbound and westbound were closed because of an accident, and traffic was being diverted at mile markers 193, at Arkansas 11 north of Hazen, and 201, at Arkansas 33 near Beulan.

Entergy at 1:30 p.m. had more than 4,200 customers without power. More than half were in Independence County and there were more than 600 outages each in Stone and Pope counties.

Randy Ort, a spokesman for the Arkansas Department of Highway and Transportation, said roadways with at least ice patches on them were a problem in much of the northern half of the state early Thursday. A map of current conditions is available here.

"We've got temperatures that are literally right hovering at freezing," Ort said before the morning rush. "So you're talking about 1 degree or so in either direction could change things very quickly."

Hundreds of highway workers have been treating and clearing roads since Wednesday morning, when wintry weather started in the western edge of Arkansas.

"It's been a long night for our crews," Ort said. "This is what we don't like. This is an ice event. This is not a snow event. Crews have been out all night throughout most of the northern half of the state and we're going to continue those efforts."